To provide passenger compartment comfort, vehicles have the capability to heat or cool the passenger compartment. Conventional vehicles use waste heat from the engine as the sole source of heating for the passenger compartment. With the advent of Battery Electric Vehicles (BEV), there is no longer any waste heat available so that other means of heating the passenger compartment are required. A typical BEV may use an electric heater to warm the passenger compartment. Similarly, Hybrid Electric Vehicles (HEV) pose different problems because the engine may not always be running and generating waste heat for use by the heating system. Plug-in Hybrid Electric Vehicles (PHEV) compound this issue by running with the engine off for significant periods of time. In order to provide optimal fuel economy benefits, it is desired to heat the passenger compartment without having to rely solely on engine waste heat.
In a heating system, there may be valves to alter the flow of coolant through the system. These valves may be activated via a controller to a desired position. During normal operation, the valve will actually be in the actuated position set by the controller. During fault conditions, the valve may be in a position other than what the controller has selected. It is desirable to detect these situations in order to ensure that the system operates in a manner consistent with the actual valve position.